On Thu, May 23, 2019 at 12:25:37AM -0700, john.hubbard@xxxxxxxxx wrote: > From: John Hubbard <jhubbard@xxxxxxxxxx> > > For infiniband code that retains pages via get_user_pages*(), > release those pages via the new put_user_page(), or > put_user_pages*(), instead of put_page() > > This is a tiny part of the second step of fixing the problem described > in [1]. The steps are: > > 1) Provide put_user_page*() routines, intended to be used > for releasing pages that were pinned via get_user_pages*(). > > 2) Convert all of the call sites for get_user_pages*(), to > invoke put_user_page*(), instead of put_page(). This involves dozens of > call sites, and will take some time. > > 3) After (2) is complete, use get_user_pages*() and put_user_page*() to > implement tracking of these pages. This tracking will be separate from > the existing struct page refcounting. > > 4) Use the tracking and identification of these pages, to implement > special handling (especially in writeback paths) when the pages are > backed by a filesystem. Again, [1] provides details as to why that is > desirable. > > [1] https://lwn.net/Articles/753027/ : "The Trouble with get_user_pages()" > > Cc: Doug Ledford <dledford@xxxxxxxxxx> > Cc: Jason Gunthorpe <jgg@xxxxxxxx> > Cc: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx> > Cc: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx> > Cc: Christian Benvenuti <benve@xxxxxxxxx> > > Reviewed-by: Jan Kara <jack@xxxxxxx> > Reviewed-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx> > Acked-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> > Tested-by: Ira Weiny <ira.weiny@xxxxxxxxx> > Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx> Reviewed-by: Jérôme Glisse <jglisse@xxxxxxxxxx> Between i have a wishlist see below > --- > drivers/infiniband/core/umem.c | 7 ++++--- > drivers/infiniband/core/umem_odp.c | 10 +++++----- > drivers/infiniband/hw/hfi1/user_pages.c | 11 ++++------- > drivers/infiniband/hw/mthca/mthca_memfree.c | 6 +++--- > drivers/infiniband/hw/qib/qib_user_pages.c | 11 ++++------- > drivers/infiniband/hw/qib/qib_user_sdma.c | 6 +++--- > drivers/infiniband/hw/usnic/usnic_uiom.c | 7 ++++--- > 7 files changed, 27 insertions(+), 31 deletions(-) > > diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c > index e7ea819fcb11..673f0d240b3e 100644 > --- a/drivers/infiniband/core/umem.c > +++ b/drivers/infiniband/core/umem.c > @@ -54,9 +54,10 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d > > for_each_sg_page(umem->sg_head.sgl, &sg_iter, umem->sg_nents, 0) { > page = sg_page_iter_page(&sg_iter); > - if (!PageDirty(page) && umem->writable && dirty) > - set_page_dirty_lock(page); > - put_page(page); > + if (umem->writable && dirty) > + put_user_pages_dirty_lock(&page, 1); > + else > + put_user_page(page); Can we get a put_user_page_dirty(struct page 8*pages, bool dirty, npages) ? It is a common pattern that we might have to conditionaly dirty the pages and i feel it would look cleaner if we could move the branch within the put_user_page*() function. Cheers, Jérôme
